The beginnings of the combine took place in 1977, when the workouts were conducted by three separate scouting services National, Blesto and Quadra. The system was streamlined even further in 1984, when the workouts were moved to one site. The combine is an invite-only event, closed to all but invited players and NFL team officials.

There are several reasons why the combine has become such an important part of the draft process. Among them:

All 32 teams get to watch the prospects in an equal setting, under the same conditions.

Owners, general managers and coaches have the opportunity to see most everyone who will be drafted -- all in one place, within a four-day period. There will be plenty of flying around the country for individual workouts in the weeks to come, but the combine is "one-stop shopping."

The combine is another means of helping teams make good decisions, and the escalating cost of signing first-round draft picks makes the decision-making process all the more crucial. Teams spent a total of $160 million on signing bonuses for last year's first-round picks. They want to make sure they know what they're doing.

Players stay at a hotel within walking distance of the RCA Dome. After dinner on Thursday, they will get a brief orientation on how to conduct themselves in the coming weeks (after the draft, rookies will have a three-day seminar that expands on life in the NFL).

Here is a breakdown of the certain physical and mental tests the players will go through:

40 Yard Dash
Each and every prospect can be tested in the 40 yard dash, although each and every prospect can deny to be tested. The 40 yard dash is a test of speed, power, explosion, and a little bit of conditioning. Each prospect will be measured by the second and how long it takes you to complete a 40 yard sprint. The 40 yard dash will also be timed for 10 yard and 20 yard splits to test explosion.

The Drill: From a three-point stance, a player runs 40 yards as fast as he can. He is timed at three increments: 10, 20 and 40 yards. The 10-yard time is especially important for offensive and defensive linemen because they usually don't run farther than that during a play. Players get hand-held times (by scouts using stopwatches) and electronic times (recorded by a machine using a beam).

What it tests: Pure speed from Point A to Point B under ideal conditions (indoors, AstroTurf, no weather obstacles).

Bench Press
The bench press is the biggest test of upper body strength out there. It also will test conditioning. Each player must bench press 225 lbs. as many reps as they can. Quarterbacks and wide receivers are exempt from the test. The bench press is the most important for offensive and defensive linemen.

The Drill: The player lies on a weight bench and lifts a 225-pound barbell as many times as he can. He has to lower it to his chest each time to count as a legitimate repetition.

What it tests: Strength and conditioning.

Vertical Jump
The vertical jump isn’t really the most important test for football players. It is basically a test of explosion and power. Technique is huge here. Each player will be tested by a machine that will measure how high your fingers touch when going directly up in the air. The vertical jump is the most important for receivers and defensive backs.

The Drill: Years ago, players jumped up to touch a wall that was marked in blue chalk. Now, the player stands flat-footed and raises his arm straight up. His reach is measured from the ground to the tip of his fingers with a telescopic ruler. The pole is lowered to that height. The player then jumps straight up and hits as many plastic flags as he can. The flags, spaced half an inch apart, rotate when hit.

What it tests: Vertical leg explosion.

Broad Jump
The broad jump is similar to the vertical jump. Although the broad jump measures how far you jump not how high. Technique is also important here. It is also similar to the long jump in track and field, but here the player will not run, but rather jump from a standing position. The broad jump is the best test for lower body strength, explosion, and power. The broad jump is the most important for running backs, linemen, and linebackers.

The Drill: he player puts his toes on a line and leaps forward. Distance is measured from the line to where his heels land.

What it tests: Leg explosion, quickness and lateral burst

20 Yard Shuttle
The 20 yard shuttle is one of the most underrated tests at the combine. The 20 yard shuttle is a test of speed, explosion, and changing of directions. Technique is also important here. Each prospect will be timed by seconds in how fast they can go 5 yards to their left, then 10 back to the right, and finishing 5 yards to their left in one straight line.

The Drill: The player straddles a yard line and puts one hand down in a three-point stance. He can start by going either right or left. Let's say he starts at the 5, with the goal line to his right. He runs 5 yards to his right and touches the goal line with his right hand. He then runs 10 yards to his left and touches the 10-yard line with his left hand. He finishes by running back to the 5.

What it tests: Lateral quickness, coordination and change of direction.

60 Yard Shuttle or Long Shuttle
The 60 Yard Shuttle is the same thing as the 20 yard shuttle but instead of 5, 10, and 5, it is 10, 20, and 10. The 60 Yard Shuttle is the combine’s best test of conditioning.

The Drill: From a starting line, a player runs 5 yards and back, then 10 yards and back, then 15 yards and back. He must bend down and touch the line at each 5-, 10- and 15-yard interval, for a total of six touches.

What it tests: Speed, endurance and conditioning.

3 Cone Drill
The 3 Cone Drill is the newest addition to the NFL scouting combine, replacing the “4 Cone” or “Box” drill. The 3 cone drill is also a test of speed, explosion, and changing directions. Each prospect will be timed by seconds in how fast they can sprint ten yards, back, back again and around a third cone parallel to the 2nd.

The Drill: Three orange cones are placed on the field forming an "L." Cone 1 is at the end of the L, Cone 2 is at the corner of the L and Cone 3 is at the top of the L. There are 5 yards between each cone. The player starts by getting down in a three-point stance next to Cone 1. He runs to Cone 2, bends down and touches a line with his right hand. Then he turns and runs back to Cone 1, bends down and touches that line with his right hand. Then he runs back to Cone 2 and around the outside of it, weaves inside Cone 3 (as if he were running a figure eight), then cuts tightly around the outside of Cones 3 and 2 before finishing at Cone 1 in a full sprint.

Position Specific DrillsEach prospect must go through football drills designed for their specific position. NFL coaches and scouts will follow each of the prospects, guiding them through the drills and watching their every move. The drills are somewhat overlooked since the workout numbers is what everyone seems to care about.

NFL Team Interviews
Each NFL team can chose up to 60 prospects at the combine to interview. The interviews are held at the hotel where the prospects stay and believe me questions can really, really vary.

The Wonderlic Test
The wonderlic test is similar to the I.Q. test everyone in the world knows of. Although the Wonderlic is definitely is not the same. The Wonderlic taken at the Combine takes 12 minutes and contains 50 questions. The test is also designed so most prospects do not finish in time. For more information on the Wonderlic Test go to http://www.wonderlic.com

The Measurements
Each prospect is measured with their height, weight, arm length, and hand length. Also running backs and linemen’s body fat percentage will be measured.

The Cybex Test
The Cybex Test isn’t the most important test prospects must go through. Although, injured and previously injured prospect’s results in the Cybex Test will get serious looks from coaches. The Cybex Test will test the flexibility and joint movement of each prospect. Each prospect will be hooked to a machine which will determine their results.

Injury Evaluation
Each prospect will go through X-rays and physicals to determine their current injuries and their injury histories. Injured prospects coming into the combine will get serious looks. Few prospects really come out of the combine with injuries they did not know they already had. Also each prospect will take a urine test to check for substances that are not allowed in the NFL.